Abstract: This paper aims at the water inrush event of roof bed separation in the goaf when the working face 106A in Shilawusu mine advances 550 m away. On the basis of field measurement and theoretical analysis, the mechanism of this water inrush event was deeply studied. The results show that the closed separation area water under the cretaceous giant sandstone 310 m away from the coal seam is the source of this abnormal water inrush event. According to the overburden deformation and failure fiber optic monitoring drilling 3.0 km away from the 106A working face, the ratio of the height of the fractured zone to the mining height is 24.56, the calculated water flowing fractured zone would not develop to the position of bed separation under cretaceous giant sandstone. However, the loading transfer effect of separation area water leads to the failure of the rock layer between the water flowing fractured zone and the bed separation, which makes the water flowing fractured zone connects separation area water, forms water-inrush event in roof bed separation.